Some commercial examples of combination hand tools, specifically designed with opposite ends for engaging different size fittings of English or metric nuts and bolts include: open-end and box-end wrenches; flex-box wrenches, standard and offset ratcheting box-end wrenches and open-end/socket-end wrenches, to name a few. Except for the conventional hand driven single-ended socket wrenches, each of the tools described is available in several combinations of sizes to engage more than one size fitting of nut or bolt, whereas a conventional hand driven English or metric socket is tooled to fit only one specific size nut or bolt. This necessitates auto mechanics, machinists, electricians and consumers to purchase a large number of individual single-ended regular depth and deep well sockets to make up a reasonably complete tool set that will accommodate several different jobs. Since foreign imports, such as automobiles, machinery and electronic equipment are assembled with metric fittings and many American made products incorporate English and metric nuts and bolts, separate metric socket wrenches must be purchased, which further increases consumer costs.
Added to this dilemma are the following familiar frustrations and shortcomings experienced by tradesmen and consumers who own large tool sets containing several sockets:(1) An increase in the loss of individual smaller sockets from a set, (2) English and metric sockets often get mixed together in a tool box, causing (3) A significant loss of time on the job, which results in a loss of money when trying to locate the correct size socket for a specific fitting and (4) The added weight of a tool box containing a complete set of regular depth and deep well English and metric sockets. All of the aforementioned disadvantages experienced with conventional single-ended sockets are overcome by the present invention.
U.S. Pat. Nos. 1,469,589, 1,478,736 and Canadian patent No. 735,672, show double-ended sockets with an internal axially central square drive well, accessible from either open socket end by a conventional extension rod for driving the tools. However, these patents do not combine English and metric sizes in one tool, nor can the tools described be used to engage and turn hexagonal nuts on protruding bolt studs.
No where in the patents cited or for that matter in any other publication, has it been found or would it be apparent to one skilled in the art, that double-ended sockets are designed to engage and turn hexagonal nuts on protruding bolt studs, or are tooled for an English size fitting in one socket cavity and tooled for the closest metric equivalent size fitting in the opposite socket cavity.
In none of the prior art examined is there any reference to a complete tool set using the features of the present invention, as suggested for the purpose of providing a full range of commercial sizes, nor is the pairing of closely sized English with metric sizes implied for any kind of double-ended socket wrench.